Process for the synthesis of hydrocarbons from carbon monoxide and hydrogen by means of a fluidized fixed-bed



Sept. 30, 1952 J MORAN 2,612,512

PROCESS FOR THE SYNTHESIS OF HYDROCARBONS FROM CARBON MONOXIDE AND HYDROGEN BY MEANS OF A FLUIDIZED FIXED-BED Filed Sept. 16, 1947 2 SHEETSSHEET l 1 INVENTOR.

J .N .MORAN A TTORNEVS Sept. 3 1952 J. N. MORAN PROCESS FOR THE SYNTHESIS OF HYDROCARBONS FROM CARBON MONOXIDE AND HYDROGEN BY MEANS OF'A FLUIDIZED FIXED-BED 2 SHEETS-SHEET 2 Filed Sept. 16, 1947 INVENTOR.

J.N.MORAN BY 2;: ATTORNEYS V FIXED-BED 1 Delaware i if September 16,1947, Serial No. 77l,3 85 I Claims. (c1. 2505449) This invention relates'to 'th'esynthesls of hydrocarbons by the reduction of an oxide ofcarbon with hydrogen. In one of its morespecific aspects it relatesto the synthesis of hydrocarbons by the reduction of carbon monoxide with hydrogen in a fluidized fixed-bed conversion chamber. Y

In the process of synthesizing hydrocarbons, which process is known to'the petroleum industry as Fischer-Tropsch Synthesis, an oxide of carbon, e. g-., carbon monoxide; and'hydrogen are reacted together at suitable. elevated temperatures in the presence of oi-selected catalyst to yield higher boiling organic compounds, including hydrocarbons ranging from light gaseous methane to heavy liquids 'orwaxes. Catalysts commonly used for this synthesis are sintered iron, and compounds or compositions comprising cobalt, nickel, and/or ruthenium. These catalysts may be promoted-with such materials as alkali metals, alkaline earths,or their oxides, or with thoria or various other promoters. The catalysts maybe utilized in either a static fixed bed or in a fiuidizedbed. "In fixed bed operationsit is common practice to-support the catalyst on an inert supporting material such as kieselguhr or the like. Such support materials may be crushed to any desired mesh size. It is common'practice to dissolve the catalyst material and the promoters in a" suitable liquid solvent which mixture is then' mixed with the support material and 'the promoter and catalyst materials are precipitated from their solution by means of an alkaline solution. When utilizing the fluidized catalyst modification of this synthesis, in which a catalyst in the form of a freely flowing powder is normally suspended in the gaseous material passing through the reaction zone, the promoter material is usually fused into the catalyst and'the resulting hard mass is ground to a relatively hard, abrasionresistant powder.

When synthesizing hydrocarbons utilizing a static fixed catalyst'bed' it has been necessary to operate at relatively low space velocities, such as between about 100 and about 300, and the rate of production of hydrocarbons heavier than ethane has been undesirably low. It has recently been found that when fluidized fixed-bed operation -is applied to the Fischer-:Tropsch process space velocities and consequently the production rate can be greatly increased. Thus, whereas in static fixed-bed operation, space velocities of about 100 to about 300 'are'used', in fluidized fixed-bed operations, space velocities as .GARBONS FROM CARBON MONOXIDE AND HYDROGEN BY 'MEANS OFA .FLUIDIZED with a finely ground catalyst' at such a linear high as 5000 may be used, and a'correspo'ndingly increased rate of productionv of 'fhydr'ocarbons heavier'than ethane may be obtained. Inffiuidized fixed-bed operation, thesynthesis'fg'as, which comprises carbon monoxide."and'hydrogen in a molar ratio'oi from about 1:2 to 2:3,"is contacted velocity thatthe catalyst is continually ia itated and uniformly distributedllbut is not substanuau carried out of the reactor.- j

Although fiuidizedfix edbefdoperation permits increased space velocities,"it also. entails certain problems. One problem is that of maintaining the linear velocity of, thesynthesis'gas su'fliciently high throughout; the length f of the reactor to maintain catalyst fiuidizationfanifatl the same time, sufifi'ciently low to prevent'uiidesirably high yields of lighthydrocarbdnssuchas'methane and also to prevent undesirably, high temperatures nearth'ef inlet of the reactor." This problem is accentuated in the Fischer- Trop'sch process, since as a result of the union of carbon monoxide with hydrogen to form normally liquidfproducts, the

gas volume continuously decreases vjduring passage through the reactor. v

* An object of the present invention is to provide an improved reactor for {the synthesis of hydrocarbons by the reduction of carbon 'iiionoxide with hydrogen. Another object is'to provide an improved reactor for such synthesis iniwhich fluidizatlon of the catalyst, .isfacil'itated. Another object is to provide animproved reactor for such synthesis in which the removal fof heat of reaction is facilitated; Another object'is to provide a method for conducting the synthesis of hydrocarbons by catalytic reduction 'ofllcarbon monoxide and hydrogen using'the 'iinproved reactor of the, present invention. .',Another object is to provide 'a'me'thod for maintaining .linear velocities through a reactor. "Anotherobject is toprevent undesirably high, temperatures near the inlet of a reactor. Othera'nd further. objects will be apparentt'o those skilled'in the art upon study of the accompanying descriptionand drawings. 3 i n v The present invention provides a solution for the problem of'maintaining'linear velocity of the synthesis gas throughout the length ofa'fiuidized fixed-bed reactor. Understanding of the invention'will be facilitated by reference tothe accompanying diagrammatic drawings. Figurel of the drawing is across section viewfof a Fischer- Tropsch reactor designed in accordance with this invention. The reactor comprises a plurality of unobstructed reaction'chambers II a, 'Hb, Ho and II which are preferably disposed in-a-substan-.

eter of throats l2a b and c is of such size as to allow the floyv; of synthesis gas and catalyst therethrough but is preferably of a cross sectional area not greater than one-fourth of the maximum cross sectional area of the reaction cham'-" ,lO throats is not critical butt'they'are preferably cylindrical and have extendingconical members bers. The shape of the reactionchambers and closing each end of said chambers. The conical shaped members substantially reduce: deadareas within the chambers. Inlet means,- such as con-j duit I3 is provided to convey synthesis gas from a synthesis gas supply into the lower portion. 015 reaction chamber Ila enclosing a reaction zone therein. Outlet means, such as conduit I4- is provided to convey the efliuent from the upper portion of reaction chamber H d. Outer; chamber T51Sflizrdundsthe. plurality of reactlonlchaznhers"v and connecting conduits, and forms a. cooling zonein thespafcie 1 between the outerv chamber and the reaction chambers and: connecting: conduits, "'gioolantfiinlet' means, such as conduit] 6 is 'provided' in the, upper portion of the outer chamber {for the" purpose of conveying a. cooling fluid into the coolingzonej; Codlarit outlet-means, such as conduit I1, is" provided 111 the 'lower p'ortion of the. outer cha'mber 'for the purpose of removing cooling fluid therefrom. Coolingi'fiuid l't may be water, a heavyoil',;o'r any other coolant to be, suitable for useror the removal of heat from" a; reaction. zoneby indirect heat exchange Particulate; or. powdered catalyst I9 is preferably contained. within the reaction. chamberye, g:,.11: 1. ;1ower two-reaction zones may be filled'wi'th catalyst before the'start-up and will bedis'tributed to: the remaining reaction zones by theifiow'of synthesis gas; The. catalyst. may be any one? off the catalysts suitable for-Fischer! Trop-sch 'synthe's'i's1 It is preferred, however, ,t o

use a catalyst prepared. by'fusing, iron oxide, cooling-and grinding the fused material to a size Within the range of from abdutififi to. about 100 and'reducin'g the. ground material with hydrogen;' I Alkaline'promoters, suchas.- .p ota ssiumfcarbonate or barium. hydroxide, may be 1; sr rhesisgas Comanche-hydrogen and b monox'idein a molarratio 6f about 312' and; an,

inert diluentf 's'uch as' nitrogen. is introduced into the reactioirzones through. inlet [3. Whencatalyst material has been preeharg'ed tov thereaction zones; only jsufii'ci'ent' amounts of the particulate catalystare added with the synthesis gas to make up the lossofcatalyst throughoutlet conduit l4. Ifcatalystmaterial'is notlprecharg'ed to thereaction zcnes,;s'ufiicient catalyst is fed to the reactor withi'thesynthesis,gas. to'get the desired reaction. The synthesis gas enters the reaction chamber through inlet. [3* at a; relatively high velocity, which velocity decreases within the reaction zone. With such velocity, however, the catalyst contained inv the reaction done. of chamber I la is substantially entirely fluidized. A portion of the carbon monoxide and hydrogen will. coact therein to form hydrocarbonsin the reaction zone. A The: synthesis gas, reaction products. and a portion or the catalyst then pass through communicating c'oriduitflZa at an increased. velocity which .sub-

stantially fluidizes the catalyst contained in-the reaction zone of chamber b. Upon passing into;

"4" I reaction chamber III), the velocity of the gas once more diminishes. These steps are repeated in the passage, of the synthesis gas, products, and

a small portion of the catalyst through the re- 7 mainder of ,th' communicating. conduits and reaction-zone The diluent of} the synthesis gas is'o f a' sufibclen't vomme'tc furnish the desired .velocity in passing from one reaction zone through the communicating zone into the succeeding reaction-Zone. By this combination of restricted communication zones and larger reaction zonestoge ther withthe use of a diluent gas,

the linear'veIoc'i-ty is substantially maintained throughout the entire length of the reactor, and [channeling le -obviated, or at least greatly minimized. Separation means (not shown), such as a cyclone separator or a Cottrellelectric precipitat'o'r, may be provided in conduit [4 for the purposeof separating entrained catalyst from the reactor effluent stream-" The diluent gas may also be separated from the. ef fluentstreamat substantiallyrthe'. sariiI-point The catalyst and diluent gas'niayf'then'he' recycled to inlet conduit I-3 and reds: v jthe synthesis process. 7 r

su table cooling. fluid such asswater, heavy oil, or"a'iiyother conventional coolant fluid is injected into'the' cooling zone througl'rcoolant inlet I6 and, is caused to passcountercurrently to the direction or, flow; or; the synthesis-gas within the reaction. and. communicatingtzon'es and is removed? from/the coolant zone through coolant outlet? 11 A 1 1 the d vi e vpf; this invention, the tempe 'ture ot'r'eactior'tis much-more easily controlled" by v thefincreasedcooli-ngg surface; since more complete indirect eontactbetween; the syn-- thesis gases" andIthecooling fluid-is: obtained. A portion of the-heat isremoved while the" gas is still in the reaction zfoneandanadditional portion is. removed. as the gasesr pass througl'ithe smaller communicating-conduits; V

Suitable. reaction; conditions a Fis'cher Tropsch process using areactorot the present invention "are a temperature; within the range" of etwe n; about.v 300.; and 1 about 320 (5t,- a pressure betwenaboiitmend-about 20 atmospheres, and an overall.-spacevelocity between about 7 1500 and about.- 5000; volumes (SIPiof synthesis" gas: per? volume or, catalyst per hour.

Figu'rfezds aisectional-view or a preferred'modificatitin, of the reactor of ther present? invention; Th reaction chambers 2| (1,, 2 l 2);. 2 l c. and. 2 Id; en cljej rig reaction zones-therein, are-'similar" to v A e andgdi'shownin Figural, thej'exc'eption tha the-chambers decrease in late; 21d. pemmunicating com duit means -.2 11,; ai id care similarto command-- catiiigjcon'dui ts. l zd hander Theicrosssectional areas of j. conduit means 22a; 1 21,-, and c shoulde be 0- g at eh tharr one fou-rthct theoross-sectional areaof the larger. or glower of the. reaction: chambersbetween. which eachcomment;ates.= Synthesis gas is introduced into reaction'chamber 2.1a through inlet means; sucltjas oonduit: 2 3. at a sufiicientvelocity tog fiui d-izenthercatalyst. either contained in the; r action? zone; or carried into the: reaction 'zonejby the synthesis gas; 1 the" reaction zone theyelacity-decreasesrsubstantially nicating zones.

such as. conduit-24.; Any conventional separation means (not--- shown) .may be provided in-zconduit 2.4 to separateentrainedcatalyst from the effluent stream.. ThisWseparated' catalyst is recycled. to inlet conduit .23iand is reused in the synthesis process. Outerchamber 25 surrounds the'series of r eaction chambers and.,communicating con.- duits and maybe. oi anydesired. shape.v It is nccessaryonly that the outer chamberbe large enough toprovide'sufiicient space-therein'for the coolant which is used in indirect heat exchange relation with the-materials within the reaction and communicating; zones. The outer chamber 25 is provided; in'its upper .portion with a coolant inlet meansgsuch as conduit 28 and in its lower portion with a coolant outlet means, such as conduit 2T. cooling fluid l8. Particulate catalyst 29 may be any conventional Fischer-Tropschcatalyst. The

cooling fluid, as in the reactor shown in Figure 1, is caused to pass countercurrently; within the outer'chamber, to the direction of flow .01 the synthesis gas within the reaction and commu- In the operation or the device of the reactor shown in Figure 2, a diluent may be used as part of the synthesis gas. '.A part of its purpose is, however, replaced by the reaction chambers .otdiminishing volume through the "reactor. As the volume of the synthesis gas diminishesb'ecause of the reduction of the carbon monoxide andhydrogen, the gas is passed into a reaction zone having a smaller volume than the next preceding reaction zone thus allowing the synthesis gas and reaction products to maintain. fiuidizing linear velocity through the reactor and a corresponding space velocity is maintained at corresponding positions in the reaction zones. The reactor of'Figure 2 is therefore preferred for synthesis gas containing substantially no diluents or relatively small proportions of diluents.

Figure 3 is a cross section horizontal view taken along line 3-3 of Figure 1. Figure dis a cross section horizontal view taken along line 4-4 of Figure 2.

Although each of the reactorsshown in the drawing discloses the use of four reactionchamhere, the invention is not limited to any speciflc number of such chambers. It is necessary only that a suflicient reactor length be provided Cooling fluid 28 may be the same as catalyst, .fluidization of thejcatalyst throughout thereactor isdiilicult to maintaimj Under reaction: condition of aninitial inlet: temperature of 315, C.,- ajpr,essure of atmospheres and space velocity of 2500 volumes ofisynthesis 'gas'per vol-.

ume ofcatalystjperhour,ithecatalyst near the inletis -satisfactorily fluidized; but the catalyst further downstream-ls not.- ;;Theresult is that synthesis gases further downstream'are substan' to secure the desired reaction of the synthesis gas.

Temperatures in a Fischer-Tropsch process must be confined within relatively narrow ranges,

depending upon the catalyst used. These temperatures, for the specific catalysts, are well.

known to those skilled in theart. One of the additional advantages of a reactor constructed in accordance with this invention as compared with conventional cylindrical reactors is that increased efficiency is obtained in the removal of heat of reaction produced by the reaction of the carbon monoxide with the hydrogen. The increased eificiency of heat removal is a result of the relatively large chamber surface exposed to the coolant and also of the greater amounts of synthesis gas caused to contact the cool surface.

Example In a Fischer-Tropsch reactor in which hydrotially; unreacted=.; Increasing; the overall space velocity sufiiciently to fiuidize-all. of the catalyst results in anundesirably high itemperature'at the reactor inlet, and :an: undesirably high proportion of. the, unreacted carbon monoxide is convertedtomethane.

p When-a reactor similartothatinFigured. comfactory yields --of. liquid hydrocarbons are obtained;-

..- Other embodiments of the invention may also begwconstructed, for example, several separate series of reaction chambers of the types'shown in Figures; t1 .-,and 12 may be operated in parallel insides single pooling jacket. Another desir-. able-modiflcation-is to reverseithe flow of fluid through ,ithe cooling chamber, injecting a liquid through conduit I! or 21, cooling the reactant material by'vaporizing the liquid and. removing the vapor through conduit It or 26.

Although this invention has been described with some particularity, it is clearthat many modifications and changes may be made by those skilled in the art without departing from the scope and the intent of the invention.

I claim: I

1. A fluidized fixedhed method for synthesizing hydrocarbons by the reduction of hydrogen and carbon monoxide which comprises the steps of introducing all of a synthesis gas comprising hydrogen and carbon monoxide into the lower portion of afirst unobstructed reaction zone of a reaction chamber at a reaction temperature and at a velocity sufiicient to uniformly distribute a particulate catalyst within and throughout said unobstructed reaction zone; passing said syn-v passing said synthesis gas and reaction products through at least one more unobstructed constriction zone and at least one more unobstructed reaction zone successively smaller than its im-- mediately preceding reaction zone of said reaction chamber, the supplying of gas to the lower portion of said first reaction zone being the sole V supply of gas-to said reaction zones; maintaining the overall space velocity throughsaid reaction zones at between 1500 and 5000 volumes (STP) of gas per volume of catalyst per hour so that a corresponding space velocity is maintained at corresponding positions in the reaction zones; passing a coolant through a cooling zone surrounding the length of said reaction zones and constriction zones of said reaction chamber so as to remove resultingheat of reaction at the periphery of said zones from the materials within said zone; removing said reaction products and a I and irebycling. said catalyst 'oniyito 'gaidz flrst m a j a smait portiori 'ofiaigiieataiyst Hai a-the 1ast sfie= cessive'zone 'ot eaizi: .z eaction onambei ;}s'ep'aratnig saidresultmg; vream-Jonpro-duets, and said catalystobstructed reaction zone: ti 2. i-The' method of claim iy-whereirig-asubstantiaHyr'ineft' diluent gas i supol-ied tosaia reation zori'es 'with said syxithesie gas; a

. 3 A fluidized-' fixedbed methoditor synthesiz jug-hydrocarbons by th iductibi'ifif hydrogen and carbon monoxide which ooii p ises'the 'steps of introducing allw a synthesis gas: coinpfisin'g hydrogen and 'oarbori mog-oxide: into -the lower portion of a firstunobetructeckre imen-zone or a reaction chamber at a reaction fie'riifiei atiire afid at a :velocity ufiioieiit toguriifoi'mlwdisfiri-bute a particulate ioatalysfl wi-thin and -tliroughoilt' am first reaction'zorfe pQlsisiiI-iQ'SaifiYfitIi gas andresulting. reaction products P thfough 1m *imo'b structed constriction zone-'ot saiq reactiorioham ber into: a second unobstructed- :reaotioii zone of a smaller volume'fithan saiwfiist reaetion' zone with sumcient velocity tosim-iiafly uniformIy-dis' tribute particulate catalyst therein; similarly passing" said :synthesisgas and reaction products through-at leastone mor 'e unobstruetedeofistrictlon .zone and at leastionemore'unobstructed reaction zone successively smaller than itsimmediately :preceding reaction izone' of aid reaction chamber; 'mainmining the" overa Space velocity through said .reaotionczonee at'between ism and aeto vomm "(8TB)" of g'as per voiiime oi:- eatalys't i ei mom o h "a c rrespondingspace-velocity is mimaihedxat; mespondmg :p'oeitions in the reaetikmiz'ones zassing a ooolant througn a coolifig suiidtihdmg' the length of said u'nob stiuetedieaotion zones andoonstiiction zones of said feaotioiirohambefi: to femov'e resulting heat of rrieact'romatiithxperiphery ofgsaid zon'e's from trielmateriails withirtisai -'zones-; "removing said react-i011: zarodnetgi anfiiia: small-portion on said catalyst:rfromrftrieirlast sucbessive zone of saidreaeti'on nhazirberiis'eparatirrgi sai'dreaoti'on products andssaiizt catalystx ahdxeeyolingzsaid catalyst only common-mohair; GtEd 'TIEQCfiiOHZ'OnGZ- I I 1 JESSEJNQMORA-NL are of record-in-the 5 Murphre e etah S'charmann; 

1. A FLUIDIZED FIXED-BED METHOD FOR SYNTHESIZING HYDROCARBONS BY THE REDUCTION OF HYDROGEN AND CARBON MONOXIDE WHICH COMPRISES THE STEPS OF INTRODUCING ALL OF A SYNTHESIS GAS COMPRISING HYDROGEN AND CARBON MONOXIDE INTO THE LOWER PORTION OF A FIRST UNOBSTRUCTED REACTION ZONE OF A REACTION CHAMBER AT A REACTION TEMPERATURE AND AT A VELOCITY SUFFICIENT TO UNIFORMLY DISTRIBUTE A PARTICULATE CATALYST WITHIN AND THROUGHOUT SAID UNOBSTRUCTED REACTION ZONE; PASSING SAID SYNTHESIS GAS AND RESULTING REACTION PRODUCTS THROUGH AN UNOBSTRUCTED CONSTRICTION ZONE OF SAID REACTION CHAMBER INTO A SECOND UNOBSTRUCTED REACTION ZONE OF A SMALLER VOLUME THAN SAID FIRST REACTION ZONE WITH SUFFICIENT VELOCITY TO SIMILARLY UNIFORMLY DISTRIBUTE PARTICULATE CATALYST THEREIN; SIMILARLY PASSING SAID SYNTHESIS GAS AND REACTION PRODUCTS THROUGH AT LEAST ONE MORE UNOBSTRUCTED CONSTRICTION ZONE AND AT LEAST ONE MORE UNOBSTRUCTED REACTION ZONE SUCCESSIVELY SMALLER THAN ITS IMMEDIATELY PRECEDING REACTION ZONE OF SAID RE- 